In a slagging coal gasifier, coal or coke is partially oxidized at 1300-1600° C. to produce a mixture of CO, CO2, H2 and H2O (syngas). The coal typically contains up to 25 percent by weight of inorganic minerals that combine to form a low viscosity molten slag, which contains SiO2, Al2O3, CaO and iron oxide.
The walls of the gasifier are lined with refractory material, which is typically prepared from Cr2O3 grains or a blend of Cr2O3 and Al2O3 grains, formed into bricks and sintered. The refractory material has a connected pore structure and is quite porous. As the slag flows along the walls of the gasifier, it infiltrates into the pores in the refractory material. This infiltration causes refractory degradation through a combination of grain dissolution, grain undercutting and macrocracking.
U.S. Pat. No. 6,815,386 to Kwong et al., discloses the use of phosphates to reduce slag penetration in Cr2O3-based refractory material. Phosphorous compounds are applied to the refractory material or are added to the matrix binder of the refractory material and heat treated to form phosphates.
What is needed is an improved treated refractory material for minimizing the penetration of liquid slag and an improved method for treating the refractory material.